Re: [PATCH v3 2/2] worktree add: add --orphan flag

[Jacob Abel <jacobabel@nullpo.dev>]

On 22/11/15 07:19PM, Eric Sunshine wrote:
> On Tue, Nov 15, 2022 at 6:27 PM Ævar Arnfjörð Bjarmason
> <avarab@gmail.com> wrote:
> > On Tue, Nov 15 2022, Eric Sunshine wrote:
> > > On Tue, Nov 15, 2022 at 4:13 PM Ævar Arnfjörð Bjarmason
> > > <avarab@gmail.com> wrote:
> > >> But for this patch, it seems much better to link to the "checkout" docs,
> > >> no?
> > >
> > > Sorry, no. The important point here is that the --orphan option being
> > > added to `git worktree add` closely follows the behavior of `git
> > > switch --orphan`, which is quite different from the behavior of `git
> > > checkout --orphan`.
> > >
> > > The `git switch --orphan` documentation doesn't seem particularly
> > > lacking; it correctly describes the (very) simplified behavior of that
> > > command over `git checkout --orphan`. I might agree that there isn't
> > > much reason to link to git-switch for "more details", though, since
> > > there isn't really anything else that needs to be said.
> >
> > Aside from what it says now: 1/2 of what I'm saying is that linking to
> > it while it says it's "EXPERIMENTAL" might be either jumping the gun.
> >
> > Or maybe we should just declare it non-"EXPERIMENTAL", but in any case
> > this unrelated topic might want to avoid that altogether and just link
> > to the "checkout" version.
>
> Even better would be for the documentation added by this patch to be
> self-contained and not bother linking anywhere to further explain
> --orphan. That would satisfy your concern, I think, as well as my
> concern that `git checkout --orphan` documentation is inappropriate
> for `git worktree add --orphan`.
>
> > > If we did want to say something else here, we might copy one sentence
> > > from the `git checkout --orphan` documentation:
> > >
> > >     The first commit made on this new branch will have no parents and
> > >     it will be the root of a new history totally disconnected from all
> > >     the other branches and commits.
> > >
> > > The same sentence could be added to `git switch --orphan`
> > > documentation, but that's outside the scope of this patch series (thus
> > > can be done later by someone).
> >
> > I think I was partially confused by skimming the SYNOPSIS and thinking
> > this supported <start-point> like checkout, which as I found in
> > https://lore.kernel.org/git/221115.86edu3kfqz.gmgdl@evledraar.gmail.com/
> > just seems to be a missing assertion where we want to die() if that's
> > provided in this mode.
>
> I haven't read v3 yet, so I wasn't aware that the SYNOPSIS hadn't been
> updated to match the reworked --orphan behavior implemented by v3, but
> I can certainly understand how that would have led you astray. You're
> quite correct that the SYNOPSIS should not be saying that <commit-ish>
> is allowed with --orphan.
>
> > What I also found a bit confusing (but maybe it's just me) is that the
> > "with a clean working directory" seemed at first to be drawing a
> > distinction between this behavior and that of "git switch", but from
> > poking at it some more it seems to be expressing "this is like git
> > switch's --orphan" with that.
>
> "clean working directory" may indeed be ambiguous and confusing. It's
> not necessarily clear if it means "no changes to tracked files" or "no
> files in directory". We should use more precise terminology.
>
> > I think instead of "clean working tree" it would be better to talk about
> > "tracked files", as "git switch --orphan" does, which AFAICT is what it
> > means. But then again the reason "switch" does that is because you have
> > *existing* tracked files, which inherently doesn't apply for "worktree".
> >
> > Hrm.
> >
> > So, I guess it depends on your mental model of this operation, but at
> > least I think it's more intuitive to explain it in terms of "git
> > checkout --orphan", not "git switch --orphan". I.e.:
> >
> >         Create a worktree containing an orphan branch named
> >         `<branch>`. This works like linkgit:git-checkout[1]'s `--orphan'
> >         option, except '<start-point>` isn't supported, and the "clear
> >         the index" doesn't apply (as "worktree add" will always have a
> >         new index)".
> >
> > Whereas defining this in terms of git-switch's "All tracked files are
> > removed" might just be more confusing. What files? Since it's "worktree
> > add" there weren't any in the first place.
>
> I would find it clearer not to talk about or reference `git checkout
> --orphan` at all. And, as mentioned above, it shouldn't need to
> reference `git switch --orphan` either. How about something like this
> for the description of the `add` subcommand?
>
>     Create a worktree containing no files and with an empty index, and
>     associated with a new orphan branch named `<branch>`. The first
>     commit made on this new branch will have no parents and will be
>     the root of a new history disconnected from any other branches.
>
> And then to document the --orphan command:
>
>     With `add`, make the new worktree and index empty, and associate
>     the worktree with a new orphan branch named `<new-branch>`.

I really like this approach. My original intent was that by referencing
git-checkout, users could check the source documentation for the underlying
command. Since we now call neither `git checkout` or `git switch`, just
documenting the behavior outright seems like the best course of action.